Belt drive assemblies utilizing power transmission belts capable of driving from opposite sides or portions thereof have been proposed heretofore; however, in general, these previously proposed belts employ comparatively complex structures in each of their oppositely arranged driving portions thereby complicating each of these driving belts unnecessarily and inherently increasing the cost of manufacturing such belts and the cost of the sheaves required for these belts. In addition, these previously proposed belts due to their complex driving portions are quite thick whereby substantial stresses are created in each of these belts during operation and these stresses invariably result in a reduction in the operating life of the belts.